Now, here are the Eldar army regiments. Again everything is in blue and white.

These are the howling banshees. I think they are very good in hand to hand combat. They have nearly everything you need for it. Energy weapons, first strike, good weapon skill. On the other hand they have a very low strength, low toughness and nearly no armour save.
As a conclusion I take them if I have to fight agains enemies with high armoursave like marines.

Then we have the warpspiders. They have good armour save and a good movement but no offensive capability. On top of that they are very expensive. The only cause to include them is because they look so good and tend to distract the enemy.